This invention relates to a mobile device for measuring the wear of a radioactively marked machine component by sensing the presence of radioactive abraded particles (hereinafter referred to as "wear fragments") which are contained in lubricating oil or other lubricant serving as a carrier liquid. The carrier liquid is introduced through an inlet tangentially into a flow-through chamber, then is passed in front of a radiation detector and is eventually withdrawn from the chamber through an outlet. The chamber at least partially surrounds the radiation detector and is itself surrounded by a radiation shield.
For measuring the extent of wear with radionuclides in an environment including a lubricating circuit, generally the wear with respect to the activity of the lubricant is measured. In case a modification of the internal lubricant circuit is not considered, such a flow-through measuring method is by far the most sensitive. In this connection, reference is made to Stegemann and Kaspar-Sickermann, Methoden und Ergenbnisse der Verschleissmessung an Kolbenringen mit Hilfe radioaktiver Isotope (Methods and Results Pertaining to the Measurement of Piston Ring Wear by Means of Radioactive Isotopes,), appeared in Issue 18, 1961, published by Forschungsvereinigung Verbrennungskraftmaschinen e.V., Frankfurt/Main.
The principle of the flow-through measuring process is based on the condition that the wear fragments abraded from the radioactively marked machine (engine) components are first introduced into the lubricant circuit. The lubricant is withdrawn from the deepest location of the pan by a pump operating independently of the engine and is driven back into the engine through a measuring chamber surrounding a radiation detector. The detector is generally constituted by a NaI(Tl) scintillation crystal which has an energy resolution capacity sufficient even for the three-component measurements, as well as good responding probability. The gamma radiation sensed by the scintillation crystal makes possible a determination concerning the type and the quantity of the fragments present in the lubricant circuit. The energy of the gamma quanta characterizes the components exposed to wear, thus making possible the separation of the various proportions of wear in case of multiple-component measurements. The intensity of the radiation, that is, the recorded count rate, is a measure for the quantity of the wear fragments.
German Laid-Open Application (Offenlegungsschrift) No. 22 61 667 discloses a measuring device of the type outlined above. The base of the flow-through chamber has a funnel-shaped configuration and has an outlet at its deepest location. This measuring device, however, is disadvantageous because, due to its substantial weight, it cannot find application in smaller vehicles or mobile systems and, further, it needs, for the detector, a cooling system (operating, for example, on the principle of water cooling) which can be adapted to mobile systems only with difficulty and only in a complex manner.